In a recording device using magnetic recording media such as hard disk drives (hereinafter “HDDs”) and the like, traces of data are left due to remaining magnetism even after the data is deleted in response to a file delete command or data block delete command prepared in and issued from an operating system (hereinafter “OS”) or the like. Thus, the recording device has a possibility that a third party may read information from the recording device even after deletion of the information. In order to more reliably prevent a third party from stealing data and the like using remaining magnetism, a so-called shredding needs to be performed. In the shredding, data consisting of fixed values or random values is repeatedly written to the same storage area.
For example, consider a case where data is migrated to an archive device which is a read-only storage device from a file storage where data read/write is constantly executed by a computer such as a client device. Then, the data stored in the archive device is deleted upon expiration of the storage period of the data. At this time, shredding is performed on the data blocks of the file storage in which the data was stored before the migration.
Patent Literature (PTL) 1, for example, describes a technology of securely deleting data to be deleted in a remote copy environment including a first storage device and a second storage device. Specifically, when receiving a data delete request, the first storage device determines whether a volume to which data of a volume of the first storage device is copied exists in the second storage device. When determining that the volume exists, the first storage device also transmits a data delete request for the volume of the second storage device. Thus, the data is securely deleted.